Ancient child skull shows no soft spot to accommodate growing brain

Modern-day babies are born with a soft spot in their skull, which is also known as fontanelle. But the skull of an ancient child Australian anthropologist Raymond Arthur Dart first claimed to be the missing link between humans and apes, appears to have no soft spot at all to accommodate the growing brain.

Two years ago, a group of researchers led by Dean Falk, from the Florida State University in Tallahassee, hypothesized that the Taung skull has several features that can be found in present day humans. This includes the soft spot that modern day babies are born with, adding that other more-recent hominins, the group consists of modern humans and their now-extinct relatives, may also have the same features.

A new research on the three million-year-old skull of the Taung Child, which was discovered by quarrymen in Taung, South Africa in 1924 and considered as an evidence that the Australopithecus africanus was the ancestor of the modern human, however, did not find evidence that the skull exhibits a key feature found in the skulls of present-day humans.

For the study "New high-resolution computed tomography data of the Taung partial cranium and endocast and their bearing on metopism and hominin brain evolution", which was published in the Proceedings of the National Academy of Sciences on Aug. 25, Ralph Holloway, from the Department of Anthropology of the Columbia University in New York, and colleagues, used Microfocus X-ray Computed Tomography (CT) to examine each layer of the ancient skull, which belongs to that of a child between 3 to 4 years old and is considered the oldest and best preserved skull of an early human child.

Analysis of the scan did not find evidence supporting the idea that the skull of the Taung Child exhibits human-like development. The CT scan revealed more details on the edges of what some scientists believe were skull plates and showed that the borders were not as sharp as could be expected had there been a soft spot.

The findings suggest that the brain development of the Australopithecus africanus was different from that seen in humans prompting the researchers to suggest re-examining other hominin fossils using the same high-resolution scanning technology that they used.

"We've demonstrated the misdiagnosis in Taung, and we believe it would be prudent to assess whether the presence of these features - unfused metopic sutures and open anterior fontanelles - may have been misdiagnosed in the additional specimens," said study co-author Kristian Carlson, from the University of Witwatersrand in Johannesburg.